1. Field of the Invention
The invention relates to a sheet-fed scanning device, and more particularly to a sheet-fed scanning device using a sheet-feeding power source, which is also used for moving documents to be scanned, for calibration.
2. Description of the Related Art
When a prior art sheet-fed scanner performs a color or brightness calibration, a calibration sheet is firstly transported into the scanner as a calibration basis for the standard color or brightness before the scanner scans a document. However, the calibration sheet tends to be lost and the calibration method is not very human-oriented.
In another method, a scanning module of a scanner only scans a single scan line on a calibration sheet, which is located in the scanner, as a calibration basis for the standard color or brightness. However, when the scan line is contaminated, the calibration basis for the standard color or brightness becomes inaccurate.
In still another method, a motor and a gear set, which are different from those for driving the sheet-feeding module, have to be used in conjunction with a detector for detecting a position of a calibration sheet so as to scan a plurality of scan lines on the calibration sheet as a calibration basis for the standard color or brightness. When the calibration has to be made, the motor rotates to move the calibration sheet into the range of the scan window. After the scan lines have been scanned, the detector detects the position of the calibration sheet and the motor is controlled to reverse the calibration sheet out of the range of the scan window and back to the initial position.
In this calibration method, a dedicated set of a motor, a gear set, a detector and associated control circuits is needed. So, the number of components is great and the cost is high.